1. Field of the Invention
The present invention relates to a transmission embedded in a hub of a bicycle and a transmission method thereof, and more particularly, to a transmission for use in a motor to and a pedal-powered vehicle and a transmission method thereof, which may be commonly applied to an electrically-driven bicycle or a scooter in which a motor is embedded or a conventional pedaling bicycle.
2. Description of the Related Art
Conventionally, a bicycle is means for transport in which pedals are driven by at least one human power to rotate wheels so that it may be moved forward.
Such a bicycle has been developed to be electrically-driven by a motor instead of the human power.
In the electrically-driven bicycle, an accelerator may be manipulated to control the rotary power of the motor so that the speed of the bicycle may be controlled from a lower speed to a higher speed. The electrically-driven bicycle driven by the accelerator as described above has been referred to as a scooter-type electrically-driven bicycle.
Further, there is a pedal-assistant-type or PAS-type electrically-driven bicycle in which the rolling motion of the pedal is automatically sensed so that a motor may be rotated depending the sensed rolling motion of the pedal.
Like the conventional motor, if the rotational speed is lowered, the efficiency of a hub-type motor in which a motor is embedded in a hub is rapidly dropped, so that the driving capability of the electrically-driven bicycle or the scooter may be reduced. Accordingly, the bicycle or the scooter is required to have a transmission in order to enhance the driving force in a lower speed. The hub-type motor in which a transmission as well as a motor is embedded in the hub has been recently developed.
In such a transmission, only the input of the motor is generally gear shifted, and there is a disadvantage in that the gear shift cannot be executed if a transmission control unit is loaded while the bicycle is moved under the driving condition of the motor or the pedal.
There is another problem in that, when the input of the motor and the input of the pedal is introduced into a single transmission, it is not easy to convert these inputs to a required transmission stage during the driving condition of the motor or the pedal.